Control mechanism for electrically-operated burners



May 31, 1927.

J. C. JOHNSON CONTROL MECHANISM FOR ELECTRICALLY OPERATED BURNERS Filed Nov. 26. 1926 INVEN TOR. JESSE C. JOHNSON BY M ATTORNEYfl.

Patented May 31, 1927.

STATES JESSE C. JOHNSON, 0F OAKLAND. CALIFORNIA, ASSIGNOR T0 5. T. JOHNSON CO-, 03' OAKLAND, CALIFORNIA.

CONTROL MECHANISM FOR ELECTRICALLY-OPERA'IED BURNERS.

Application filed November 26, 1926. Serial No. 150,864.

This invention relates to a control mechanism t'or electrically controlled fuel-oil burning devices.

While not limited in application, my improved safety device is more particularly designed for use in dwelling houses and is adapted for application to furnaces which may already be installed therein.

A leading feature of the present invention is the provision of means for insuring absolute safety in operation, and in this respect is to be regarded as involving certain improvements in the safety device for control systems shown and described in my prior Patent- No. 1,602,363, dated October 5th. 1926.

One of the objects of the present invention is the provision of means for controlling the operation of an electric motor, which operates the burner and supplies fuel and air for the combustion purpose, through themedium of a thermostat located in the room whose temperature isto be regulated.

Liquid fuel burners are replacing to a large degree the burning of solid fuel in furnaces of all characters. The most practical and commercially successful heating systems of this kind utilizing liquid fuel burners at the present time include electrirally operated means actuating the burner with theri'nostatic controls therefor to maintain the desired temperature in the building to be heated. It is not only desirable but usually required by fire regulations that burners of such systems used in buildings be also provided with means to cut off the supply of liquid fuel should, from any cause, the burner fail to ignite. the flame of the pilot become extinguished or in the event that uneon'sumcd fuel oil flood the combustion chamber. This object is effected by merely utilizing the thermostat as a medium for controlling an eleetro-maguetie control control. operatively associated with the main circuit switch for the motor.

Another object is the provision of means for controlling an electro magnetic control operatirely associated with the main circuit switch for the motor current, through the medium of a boiler control means responsive to conditions of temperature within the boiler.

Another object is to automatically stop the motor and the fuel oil system of the burner when the controlling circuit is opened by a manually operateitsnap switch button.

Another object is to reduce the gas supply to the pilot burner, after a. short interval of time when the burner is ignited.

Another object. is to shut down the burner system automatically if the fuel oil supplied to the burner has failed to ignite or the fuel oil supply should fail.

Still another object of my invention is the particular fashioning of my stack safety switch, wherein a coeperation of elements results in an etficiency of operation and in a simplicity of structure.

The objects of the invention thus generally stated, together with other and ancillary advantages. are attained by the construction and arrangement illustrated in the accompanying drawings forming part thereof, wherein I have illustrated a practical embodiment of the invention, in which Figure 1 is a diagrammatic View of the electric circuit control mechanism of the invention; and

Figure 2 a cross sectional view of the mercury tube of the stack safety control switch,

illustrating the. mounting thereof and connections with the stack thermostatic metal member. on line II-II of Fig. 1.

The operating circuit is obtained from conductors 11 and 12 to which the service wires 13 and 14 are connected by a double pole single throw main current switch 15, mounted on a switch board indicated by the numeral 16. Mounted on this switch board, in close proximity of the main switch 15, is an eleetromagnet 17, having an armature 18 pivotally mounted at 19, to swing into and out of en agement with the core of the magnet 17. The armature 18 is operatively associated with the main current circuit switch 15 by means of a bar member 20.

The wires 13 and 14 constitute thecircuit current connecting wires to the burner motor 21. An electro-magnetic fuel oil stop valve 22, interposed in the fuel oil supply line between the oil pump and the burner, is connected in parallel by wires 23 and 24 to wires 13 and 14 respectively of the motor circuit.

This fuel oil stop valve is preferably controlled by the main circuit switch 15 in the circuit that operates the motor, the partsbeing arranged so that the valve is held open to permit the flow of fuel oil to the burner, so long, as the current passes to the motor, and is closed to positively shut otl the supply of fuel oil to the burner, when the motor stops.

' A wire extends from conductor 12 to a room thermostat 26, illustrated diagrammaticall y, of any well known construction, which remains in a circuit closing position when cold or when the atmosphere at this place is below a certain predetermined temperature, and opens to interrupt the cirunit when the atmosphere at this place is above a certain predetermined temperature. The thermostat 26 is connected in series, by wire 27 to a boiler temperature controlled circuit breaker 28, illustrated diagrammaticall This boiler controlled circuit breaker l header of the boiler, and is arranged to flex its thermostatic member, when a steam pressure above a predetermined maximum obtains in the boiler, to break the circuit.

A wire 29, in series with the boiler controlled circuit breaker, leads to the electromagnetic coil 30 of the magnetic control 17, and wire 31 extends therefrom to a temperaias connection with the steam this case of a pin 36 secured within the casing 32.

The contactor 41, of the temperature relay, is connected by way of wire 31 to the electro-magnetic coil 30, of the magnetic a control 17, hereinbefore mentioned.

A wire 45, leads from conductor ll, to the electro-magnetic gas valve 46, by" way of wire 47, to the heat coil of the temperature relay and by way of wire 43 to electrode 49, of a stack safety switch, to be hereinafter described.

This stack safety switch consists of a mercury tube 50, swingingly supported upon the shaft 51-, this shaft being provided with a suitable holding member 52 to carry said tube, and mounted in a suitable housing ll attached to the stack of the furnace, thus having its thermostatic metal member 53 projecting into the stack and subjected to the heat of the burner gases.

Three. electrodes, 49, 54 and 55 respec tively are provided, to serve a three wire circuit.

Electrodes 49 and 54, are of the usual type and need not be further described. However, electrode 55, at its lower end, as at 56, is provided with an extension 57 substantiah ly at a right angle thereto, extending horizon till ture relay, mounted in a suitable casing intally along the lower part of said mercurya;

dicated by the numeral 32.

A temperature relay permits an electric current to flow thru it for only a limited period-of time. This particular temperature relay comprises a heating coil 33, a thermostatic metal member 34 with one end secured at 35, and the other free end thereof bearing against insulated member 36, pivoted at 37. The metallic member 34 partly surrounds the heating coil 33, and bends away from member 36, as indicated by dotted line 38, when heated by the electric current. Member 36 is connected and carries a metallic lead 39, and this lead carries contactor 40, which is held against contactor 41 through means controlled by the free end of the thermostatic metal member 34, when in a cold condition. The free end of the thermostatic metal member 34,-when heated by the electric current passing through the heating coil 33, bends towards the heating coil 33, thus allowing insulated member 36 to move downwardly by its own weight, thus removing contact-or 40, sufficiently away from contractor 41 to break the electric circuit between contactors and 41.

A re-setting member 42 passes through compression spring 43 and through a hole in fixed piece 44. Its purpose is, to enable member 36 to be forced back so as to allow thermostatic metal member 34 to spring back and reset underneath the member 36, when sufficiently cooled. To limit the dis- 'tance of the return movement in re-setting member 36, a stop is provided, consisting in tube 50, and terminating near the lower enil of electrode 54, at a distance sulficicntly great to prevent arcing when said tube is in a cold temperature position, as illustrated in Fig. 1. To limit the tilting movement of the mercury tube 5, in either direction, the holding member 52 thereof, is provided Wit 1] a downwardlyextending stem 52, as shown in Fig. 2. This stem is retained within certain limits of its movement, in either dircction, by means of two stops 52 secured within the housing H of said stack safety switch. This arrangement, including a friction clutch positioned within said holding member 52, (not shown) tends to increase the sensitiveness of the tube in relation with its thermostatic metal member 53, and results in a qlrliick response of the mercury tube 50 to c anges of temperature within the furnace stack. y

The operation of this stack safety switch is hereinafter more fully described.

A manually operated circuit control button snap switch 58, is interposed and in series with wire 31, near or adjacent to the electromagnet 17.

The shunt out circuit for the electro-magnetic gas valve 46 and for the temperature relay com rises a branch wire 59 connected by a flexi 1e lead 60 to member 39, wire 59 leading to electrode 55 of the stack safety switch. Electrode 54, by way of wire 61 is contpected to conductor 13 of the motor circu1 The structural features of electrical control mechanism including the fashioning of my stack safety switch have been set out. i will now describe the operation of the switches and the circuits controlled thereby.

The power current. is always presumed to be on conductor lines 11 and 12.

On the diagram of my electrical control circuit, Fig. 1, the low temperature contacts of all switches are shown in a circuit closing, that is in a cold temperature position. I

The starting of these circuits in operation is etl'cctcd by means of a manually operated current control button snap switch 58. When this button snap switch is closed, current flows from conductor line 12 by way of wire to-the room thern'iostat 26, by wire 27 to the boiler cont rolled thern'iostat 28, by wire 29 to the clectro-n1agnetic coil 30, by way of wire 31, which carries the button snap switch 58 in circuit therewith, tocon- [actors 41 and ll) of the temperature relay, by leads 39 and 6t) and by way of wire 59 through the electrodes and 49 of the stack safety switch, continuing the circuit by way of wire 48 through resistance coil 33, by wire 47 to the electro-magnet-ic gas valve 46, and

by way of wire 45 to the other conductor line 11.

This forms a series circuit in which the breaking of any of the lines or connections in the circuit would cause the de-energization of the electro-magnetic coil 30.

The closing of this series circuit by button snap switch 58, energizes the elect-ro-n'iagneticcoil 30 to draw armature 18 into engagement therewith, also closing the double pole single throw main circuit switch 15, operatirely associated with said armature 18 by means of an operating bar 20, thus closing the current circuit to the motor 21. This closing of the motor circuit also operates to energize the electro-magnetic' fuel oil stop valve 22 connected in parallel with the motor circuit, and a supply of fuel oil to the burner results. I

The current supply circuit to the motor is connected in multiple with the said series circuit and entirely controlled thereby by means of said electro-magnet 17.

By this arrangement means are provided whereby the motor will operate to its limit capacity immediately after the motor operating circuit is "closed by the described controlling series circuit, thus receiving the full current voltage of the conductor line.

Simultaneously with the starting of the motor 21, the electro-magnetic gas valve 16 is energized to open, permitting of a larger flow of gas to the pilot burner to temporarily enlarge the flame thereof. The fuel oil supply issuing from the fuel oil stop valve 22 is ignited by the enlarged flame of the pilot burner and commences heating the fur- After ignition has taken place, the temi J perature 1n the stack rises from the burner gases, thereby heating the thermostatic member 53 of the stack safety switch, exposed to the hot gases within-the stack, causing the mercury tube 50 to tilt from the cold to the hot temperature. position, thereby breaking the circuit between ole/trodes 4t) and 55,and closing the circuit between electrodes 55 and ,54. During this period of tilting the mercury tube 50 from the cold to the hot temperature position, in other words, during the time ol heating the thermostatic member 53 within the furnace stack, there takes place a momentary closing of the circuits between electrodes 49, 55 and 54 inclusive, thereby preventing a break in the electric. circuits when changing from the controlling circuit to the operating circuit,hereinafter described.

The closing of the circuit between electrodes 54 and 55 results in closure of the operating circuit from conductor 13 by way of wire 61 to electrodes 51 and 55 of the stack safety switch, byway of wire 59 and flexible lead 60, to metallic lead 39 to contactors 4.0 and 4]., by wire 31 to'button snap switch 58 and to the magnetic coil 30, by wire 29 to boiler control 28, by wire 27 to thermostat 26 and by way of wire 25 to coiuluctor 12.

Thus the closing of the circuit between electrodes 54 and 55 shunts out the circuit to the heating coil 33 of the temperature relay and to the electro-magnetic gas valve 46, thus allowing the gas valve 46 to close,

thereby contracting the pilot burner to its normal position. Shnnting out heating coil 33, allows 33 to cool down, and therefore thermostatic member 34 does not move away from member 36, and contactors 4t) and 41 remain in a circuit closing position, the burner then continues to operate normally.

Assuming that an excessive steam pressure is generated in the boiler or the room thermostat reaches a predetermined temperature, this will act upon either, the thermostatic control 26 or on the boiler control 28 to open their respective contacts,

- thus interrupting the control circuit, de-energizing the elcctro-magnetie coil 30. This cle-energizing of the coil 30 allows the armature 18 to fall backwards by its own weight also removing with it the main current switch 15, operatively associated with the same, to open and break the current circuit to the motor. The fuel oil stop valve 22 operates synchronously with the motor, it is opened simultaneously with the operation of the motor and is closed to positively shut off the supply of fuel oil to the burner when the motor stops.

The burner is now shut off. Meanwhile,

the thermostatic members of the room therperature or the closing position, the burner will remain in a shut off condition, until the undesirable conditions in the boiler are corrected, or the temperature of the room has lowered. The gradual lowering of the pressure within the boiler, or a reduced room temperature will eventually complete and close again the control circuits through the thermostat 26 or through the boiler control 28. This completion of the control circuit wil again automatically close the magnetic control 17 including the main current switch to again operate the motor including the fuel oil stop valve, while at the same time an enlarged flame from the pilot burner will again i nite the fuel oil, providing, the

stack sa 'ety switch has meanwhile returned to a cold temperature position by the reduction of temperature in the furnace stack.

.But should there be no ignition of the burner for any reason whatever, as when there is no su ply of fuel oil, or the fuel oil delivered s ould fail to be ignited, if

for any reason the gas pilot has blown out, there would be no resulting increase in temperature within the stack and thermostatic member 53 of the stack safety switch would receive no heat and consequently would fail to move to a hot temperature position.

The current taken to operate the electromagnetic control 17 would continue to pass through the temperature relay and particularly through heating coil 33. The heat generated in the resistance wire of the heating coil 33, under these circumstances would be suliicient, in a predetermined time, to cause thermostatic member 34 to move towards heating coil 33, to permit member 36 to fall downwardly by its own weight and separate contactors 10 and 41, thereby break ing the control circuit, which would again result in de-energizing of the electro-magnetic coil and in the opening of the circuit to the motor as above described.

This results in absolute shut down of all of the entire system, which would remain inoperative until manually re-set as previously described, after thermostatic member 30 has sufficiently cooled, before the circuit can again be closed automatically.

The above described construction of my stack safety switch and the provision of three electrodes within the mercury tube 50, to serve a three wire circuit is an important feature of my present invention.

Let it be assumed, that for any reason whatever this stack safety switch should fail to operate, asby sticking freeze when on the cold temperature position, on closing the circuit by snap switch 58, the electric current will continue through the complete series circuit above described including the temperature relay and in time cause thermostatic member 34 to draw away from member 36, to allow said member to fall downwardly and thus se arate contactors 40 and 41,

thereby breaing the series control circuit by de-energlzmg magnetic coil 30 and allow.- mg armature 18 to fall back by its own weight, simultaneously also breaking the main current circuit switch for the motor.

sticking freeze in the hot temperature position and the burner be functioning normally,

this would result in time to be effective on either the room thermostat '26 or on the boiler control 28 as previously described.

Again, assuming this stack safety switch to be sticking freeze when in the hot temperature position and the burner not in operation, in this instance, the closing of the circuit by snap switch 58, with intent to start the system in operation, cannot complete the circuit to conductor 11, the connecting in, or closing the circuit to said eonductor 11. being necessary to complete the circuit to energize the magnetic coil 30 to draw in the armature 18 to close the main current circuit switch 15, thus resulting in no delivery of current for the operation of the motor 21, nor to the magnetic oil valve 22, hence the system cannot operate, thus absolutely preventing an accumulation of fuel oil within the furnace. The motor can not again be placed in operation until the cause of this nonoperation of the stack safety switch is remedied. Thus it is evident that the completion of the controlling series circuit herein described depends upon the normal or cold temperature position of the said stack safetyswitch, V

Further it will be seen that I have provided for a rapid action of the stack safety switch elements while simultaneously breaking the control or starting circuit and changing to the operating circuit of the system without interruption of the current circuit. With the tilting of the mercury tube 50, from the cold or normal temperature position, to the hot temperature position, due to the sensitiveness of the thermostatic metal member 53, to changes in temperature, the temperature relay and the magnetic gas valve referred to, are thrown out of circuit and the system is capable of continuous operation until checked either through thermostatic means or by failure of combustion conditions that might subsequently affect my stack safety switch member. From the above description and operation it will be seen that all danger from explosion or fire,

due to improper operation, is eliminated.

I am aware that prior to my invention various forms of thermostatic controls have been used commercially for diverse purposes, and I do not claim these individual controls in detail.

llo

What I claim and desire to secure by Letters Patent is 1. In an electrical control mechanism for burners having, in combination, electric current conductors, an operating motor, a circuit connection between the motor andthe said conductors, a main circuit switch for the motor, a magnetic fuel oil stop valve connected in parallel with the motor circuit, an electromagnetic control circuit in multiple with the said motor circuit and comprisingl an electro-magnet and an armature, sai armature operatively associated with said main circuit switch for controlling its operation, in series with said electro-magnet, a temperature relay, an electro-magnetic gas valve, a manually operated circuit closing and breaking snap switch and a heat actuated three wire stack safety switch, said stack safety switch adapted, when in a cold temperature position to close the circuit to the temperature relay and to the electromagnetic gas valve on the closing of said circuit by said snap switch, the jclosing of said series circuit energizing said electromagnet for engaging said armature to close said main circuit switch for the motor current, said heat actuated three wire stack safety switch adapted, when in a hot temperature position, to simultaneously shunt out the temperature relay and the electromagnetic gas valve.

2. In an electrical control mechanism for burners having, in combination, electric current conductors, an operating motor, a circuit connection between the motor and the said conductors, a main circuit switch for the motor, an electro-magnetic fuel oil stop valve connected in parallel with the motor circuit, an electro-magnetic control circuit in multiple with the motor circuit and compris- 4 ing an eleetro-magnet and an armature, said armature operatively associated with said main circuit switch for its operation, in series with said electro-magnet, a temperature relay, an electro-magnetic gas valve, switch means for closing and breaking said circuit, and a heat actuated three wire circuit stack safety switch, said stack safety switch adapted, when in a cold temperature position to close the circuit to the temperature relay and to the magnetic gas valve on the closing of said series circuit by said switch means, the closing of said series circuit energizing said electro-magnet for engaging said armature; said heat actuated three wire stack safety switch adapted, when in a hot temperature position to prevent the operation of said temperature relay.

3. In an electrical control mechanism for burners having, in combination, electric current conductors, an operating motor, a cir-' cuit connection between the motor and the 531d conductors, a main circuit switch for the motor, an electromagnetic fuel oil stop valve connected in parallel with the motor circuit an electro-magnetic control circuit in multiple with the said motor circuit and compris ng an electr'o-magnet and an armature, and armature operatively associated wlth sa1d main circuit switch for controlling 1ts operation, in series with said electromagnet, a temperature relay, an electromagnet1c gas valve, manually operated circuit closing and circuit breaking switch means, and a heat actuated three wire stack safety switch, said stack safety switch adapted, when in a cold temperature position to close the circuit to the temperature relay and to the electro-magnetic gas valve on the closing of said series circuit, the closing of sa1d series circuit energizing said electromagnet for engaging with sald armature to close said main circuit switch for the motor current; said heat actuated three wire stack safety switch adapted, when remaining in a cold temperature position, after the closing of said series circuit, through failure of ignition, to cause said temperature relay, on failure ofthe fuel oil stop valve to operate, to automatically break the said series circuit, thus de-energizing said electro-magnetic control and breaking the circuit to the motor.

4. In an electrical control mechanism for burners having, in combination, electric current conductors, an operating motor, a circuit connection between the motor and the said conductors, a main circuit switch for the motor, an eleetro-magnetic fuel oil stop valve connected in parallel with the motor circuit, an electro-magnetic control circuit in multiple with the motor circuit and compris ing an electro-magnet and an armature, said armature operatively associated with said main circuit switch for controlling its 0peration, in series with said electro-magnet, a temperature relay, an electro-magnetic gas valve, a manually operated circuit closing and circuit breaking snap switch, and a heat actuated three wire stack safety switch, said stack safety switch adapted, when in a cold temperature position to close the circuit to the temperature relay and to the electromagnetic gas valve on the closing of said series circuit, the closing of said series circuit energizing said electro-n'iagnet for en gaging said armature to close the said main circuit switch for the motor current; said heat actuated three wire stack safety switch adapted, when remaining in a cold temperature position after the closing of said SCl'le,-: circuit, through failure of the burner to ignite, to cause said temperature relay on failure of the electro-magnetic gas valve to operate, to automatically break the said series circuit, thus de-energizing said electroanagnetic control to break the current circuit to the motor.

5. In an electrical control mechanism for lIU iii

I fill burners having, in combination, electric current conductors, an operating motor, a circuit connection between the motor and the said conductors, a main circuit switch for the motor, a magnetic-fuel oil stop valve connected in parallel with the motor circuit, an electro-magnetic control circuit in multiple with the said motor circuit and comprising an electro-magnetand an armature, sald armature operatively associated with said main circuit switch to control its operation, in series with said electro-magnet, a temperature relay, an electro-magnetic gas valve, a manually operated circuit closing and breaking switch and a heat actuated three wire stack safety switch, said stack safety switch adapted, when in a cold temperature position to close the circuit to the temperature relay and to the magnetic gas valve on the closing of said series circuit, the closing of said series circuit energizing said electro-magnet for engaging said armatureto close said main circuit switch for the motor current; said heat actuated three wire stack safety switch adapted, when remaining in a cold temperature position through failure of ignition, to cause said temperature relay, on failure of the fuel oil stop valve, or of the magnetic gas valve to operate, to automatically open said series circuit to de-energize said electro-magnet to release said main circuit switch, thus breaking the circuit to the motor, and manual means for resetting said temperature relay to again operate automatically.

6. In an electrical control mechanism for burners having, in combination, electric current conductors, an operating motor, a circuit connection between the motor and the said conductors, a main circuit switch for the motor, a magnetic fuel oil stop valve connected in para] el with the motor circuit, an electro-magnetic control circuit in multiple with the said motor circuit and comprising an elcctro-magnet and an armature, said armature operatively associated with said main circuit switch to control its operation, in serieswith said electro-mag- .switch adapted, on the breaking of said series circuit through the operation of-said thermostatlc responslve means, to prevent the closing of said series circuit automatically, unless said stack safety switch has returned to the cold temperature position.

7. In an electrical control mechanism for burners having, in combination, electric current conductors, an operating motor, a circuit connection between the motor and the said conductors, a main circuit switch for the motor circuit, a magnetic fuel oil stop valve connected in parallel with the motor circuit, an electro-magnetic control circuit in multiple with the said motor circuit and comprising an electro-magnet and an armature, said armature operatlvely associated with said main circuit switch for controlling its operation, in series with the said electro-magnet, a temperature relay, an electro-magnetic ignition means and a heat actuated three wire stack safety switch, said stack safety switch adapted, when in a cold temperature position to close the circuit to the temperature relay and to the ignition means on the closing of said series circuit,

'the closing of said series circuit energizing said armature to close said main circuit switch for the motor current; said heat actuated three wire stack safet switch adapted to prevent the closing 0 the said main circuit-switch for the motor circuit unless three wire stack safety switch, said said heat actuated three wire stack safety signature.

JESSE C. JOHNSON. 

